Extraneous output from Python code blocks using :session option

[Richard Stanton <stanton@haas.berkeley.edu>]

I'm trying to use the :session option so I can import modules, etc., just once at the beginning of my document, like with am IPython notebook. Unfortunately, the output from these code blocks contains some extraneous characters. For example:

#+BEGIN_SRC python :session :results output
a = 2
b = 3
c = 4
print 'a=      ', a
print 'b =     ', b
print 'a + b = ', a+b
#+END_SRC

#+RESULTS:
: 
: >>> >>> a=       2
: b =      3
: a + b =  5

How can I stop the production of all those ">" signs (sometimes they're dots), which don't appear if I run the same code block without the :session option?

Thanks.

Richard Stanton